1. Field of the Invention
The invention relates to video compression and decompression techniques, more particularly to a video compressing apparatus and a video decompressing apparatus that perform a reduced number of multiplication operations.
2. Description of the Related Art
Discrete cosine transform (DCT) is widely adopted in video compression algorithms, such as MPEG for motion picture coding, and JPEG for still picture coding. Similarly, inverse discrete cosine transform (IDCT) is adopted in the corresponding inverse process for decompression of compressed video data.
DCT and IDCT operations typically involve a plurality of multiplication and addition operations. In general, multiplication operations for DCT and IDCT processing are relatively time-consuming and require relatively complex hardware.
In U.S. Pat. No. 5,471,412, the entire disclosure of which is incorporated herein by reference, the applicant disclosed six-stage DCT/IDCT fast algorithms that involve only thirteen multiplication operations for one-dimensional transformation, or a total number of 208 (2.times.8.times.13) multiplication operations for two-dimensional transformation of an 8.times.8 data block. Flow graphs of the DCT and IDCT fast algorithms are shown in FIGS. 1 and 2, respectively. It is desirable to further reduce the number of multiplication operations in order to achieve a higher processing speed during video compression and/or video decompression.